This invention relates to the treatment of waste water and in particular relates to the treatment of waste water arising from cleaning food processing plants and dairies.
In recent years, municipal sewer plants have increased hook-up and volume charges to the producers of waste which require increased processing. These charges are generally based on the burden imposed on the sewer system by the contaminants produced. The municipal sewer plants must meet various environmental standards and under some circumstances may limit or deny sewer hook-ups which can effectively put the waste producers out of business or at least reduce their profitability to a comparatively minuscule level. A measure of the degree of contamination is the Basic Oxygen Demand (BOD) or initialized Chemical Oxygen Demand (COD). There are two general system methods of treatment, an aerobic system and an anaerobic system.
In an anaerobic system the waste stream after rough filtration is introduced into a closed vessel where anaerobic organisms are introduced to degrade the biological mass. Typically, there is little sludge produced and following the reduction of the biomass by anaerobic digestion the stream is passed to an aerating stage where it is aerated for about 30 days. Normally, that is sufficient for discharge into a stream or used for irrigation. Anaerobic systems are often used in the warmer climates of the United States because the system has to be maintained at a temperature of 80 degrees. The little biomass sludge produced can sometimes be used to heat the system.
In contrast, in an aerobic system, oxygen is added and the ponds are aerated continuously. They are often used in the North because temperature is not as critical in the treatment process as it is in an anaerobic system. At the end of aeration a bigger sludge mass is produced.
A need exists for a local system to drop the basic oxygen demand and the chemical oxygen demand particularly if the liquid portions can be reused rather than entering the sewer system directly or if the filtered solids can be retrieved and used as a component of animal feed. The local, or on site, system treats contaminants at the site where they originate and would be very useful where a cleaning in place (CIP) mechanism exists in the food industry. A CIP mechanism produces a large volume of solution contaminated with meat, poultry and dairy particles and mixed with cleaning agents. The contaminated solution is not mixed with body wastes until and unless the contaminated solution enters a municipal sanitary waste system.
The present invention is designed to reclaim waste water for reuse and recovery of solid particulates to avoid the sewer system for at least a cycle or two. In many circumstances, the inventive reclamation system will filter cleaning solutions and allow the reuse of the water for cleaning, conserve heat, and chemicals and anything else that can be recycled and take the solids out so that all is saved. Following treatment the solution can be reused for cleaning. The filtered solution is of sufficient cleanliness that sewage hook-up charges or use charges are greatly reduced or may even reach the degree of cleanliness to allow discharge into streams or wetlands.
Portions and elements of the present system in various aspects are known.
Milking Money from Wastewater, Dairy Foods, October 1990, discusses a European batch process characterized as a coagulation/flotation system. Air pressurized water is used to float flocculated particles precipitated from an acid solution.
A general discussion of filtration is printed in Van Nostrands Scientific Encyclopedia, 5th Edition at pages 1037 through 1040. Some of the filter types illustrated are similar to those used in the present invention.
U.S. Pat. No. 4,798,669 issued to Bruno Bachhofer et al on Jan. 17, 1989 (filed Jan. 11, 1988) describing a SYSTEM FOR TREATING WATER WITH OZONE. This basic process is similar to the invention of this application. Ozone is added to untreated water with filters downstream for disinfection. The preferred application is drinking water treatment. The filters have reducing action to remove excess ozone.
U.S. Pat. No. 5,043,079 issued to Ronald Hallett on Aug. 27, 1991 (filed Jan. 24, 1991) describing a WASTEWATER TREATMENT PROCESS WITH AN OZONE CONTACTOR. This patent covers a new contactor to apply ozone to waste water. It covers methods of blending ozone with water. This process also uses ultra-violet light to improve the process.
U.S. Pat. No. 3,835,039 issued to David Clambrone on Sep. 10, 1974 (filed Dec. 22, 1972) describing a WASTE WATER TREATMENT SYSTEM. This patent is quite similar to the process of the present application but the process is for sewage treatment and allows for recycling of water. It uses ultra-violet lamps to produce ozone with air. The treated effluent is filtered to remove large particles.
Milking Money from Wastewater, Dairy Foods, October 1990, discusses a European batch process characterized as a coagulation/flotation system. Air pressurized water is used to float flocculated particles precipitated from an acid solution.